The surface tension of solid commercially pure nickel was determined by the force measurement technique using fine wires as proposed by Udin, Shaler, and Wulff. Grain boundary measurements were also made on the same metal.
After finding experimentally that tests in a vacuum of approximately 5 x 10⁻⁵ mm Hg were unsuccessful because of the high power vapour pressure of nickel at high temperatures, similar tests were made in helium and argon atmospheres, the pressure being kept constant at 760 mm Hg during the experiments.
The average surface tension of nickel in argon was found to be 2220 ± 300 dynes per centimeter for a temperature range from 1370°C to 1390°C.
The relative grain boundary energy of solid nickel was determined by measuring the dihedral grain boundary groove angles of thermally etched nickel. The interferometric method developed by Hilliard and Harrold was used for this purpose. An average value of 161 degrees was found for the dihedral angle. The grain boundary energy was calculated to be 740± 300 dynes per centimeter.
Examination of thermally etched nickel surfaces was inconclusive with respect to physical evidence for dislocation.